Control apparatus



061:. 24, 1933. R, HATCH 1,931,656

CONTROL APPARATUS Filed Dec. 11, 192

1 l l l l l l l l l l INVENTOR ROBERT L HHT'CH BY c/ ATT NEY PatentedOct. 24, 1933 CONTROL APPARATUS Robert I. Hatch, Honolulu, Territory ofHawaii, assignor to Radio Corporation of America, a corporation ofDelaware Application December 11, 1928 Serial No. 325,208

1 Claim.

In radio signalling and especially in short wave transmission it isoften times desirable to control from a main station, a radio receiveror transmitter at a substation or auxiliary station which may be andoften times is for various reasons located at a considerable distancefrom the main station.

One purpose of such an arrangement is to increase the signalling rangeand generally the substation is located in a position where signaltransmission is favorable. Another purpose of such an arrangement is toimprove the quality of the signals transmitted due to the favorableposition of the substation.

In such arrangements signals are received at the remote station andrelayed by conductors to the main station or relayed from the mainstation to the remote point to be retransmitted.

Heretofore operation of such an arrangement has been attended by manydisadvantages such as the added expense of an operator at the remotestation, loss of time in tuning the apparatus at the remote point andloss of signal strength due to variations in signal frequency or todrifting of apparatus at the remote point.

Another disadvantage common in the operation of such an arrangement isthat the Wave band used at the transmitter or receiver cannot be readilyshifted when it is desired to signal on a different frequency.

Briefly and broadly the object of this invention is to provide anarrangement by, means of which the receiver or transmitter at the remotepoint may be tuned within certain limits from one or more points at themain station.

A further object of this invention is to provide such an arrangementwhich utilizes the tone lines between the remote point and the mainstation to carry the energy necessary to accomat the remote point.

These objects are attained by the use of a small motor at the remotepoint the shaft of which is connected through reduction gearing r to theshaft of a tuning condenser in the plate filament or grid filamentcircuit of the transmitter or receiver used at the remote point. Thefield winding of this motor is energized by current taken from thereceivers or transmitters plate potential source at the remote point.Current for the armature winding of the motor is provided by means of apair of opposed parallel connected direct current generators at the mainstation adapted by means of a pair of contacts to be alternatelyconnected in plish the tuning of the transmitter or receiver series witha lead connected to the midpoint of a repeater in the tone lines at themainstation which tone lines are connected to one end of the armaturewinding of the control motor at the substation. The direction of flow ofcurrent in the armature winding is changed by opening or closing thepair of contacts one of which is connected to the positive side of oneof the direct current generators while the other contact is connected tothe negative side of the other of the direct current generators at themain station. The armature energizing circuit is completed by groundingthe free end of each of the direct current generators at the mainstation and the free end of the motor armature winding at thesubstation. By closing one of the contacts one of the direct currentgenerators at the main station is in series with the armaure winding ofthe control motor at the substation. This causes rotation of the shaftof the tuning condenser at the substation in a predetermined direction.By opening the first contact and closing the other contact the directionof the current through the armature of the motor at the substation willbe reversed and the condenser will be rotated in the opposite direction.1

The motor shaft at the substation is connected through a reductiongearing such as, for instance, a phonograph gear train which, in turn,is connected to a Vernier dial on the condenser shaft.

Means is provided at the remote station for connecting the armature ofthe control motor across a portion of the high potential battery of thereceiver or transmitter so that preliminary adjustments of the condenserat the remote station may be made.

One advantage to be gained by the use of a device constructed inaccordance with my invention lies in the fact that the tone lines in usebetween the main station and the substation can be utilized to carry thearmature current thereby eliminating the .necessity to install otherapparatus.

Another advantage to be gained by the use of my invention is that thecontrol apparatus may be readily applied to stations now in operationwithout altering such stations in any manner.

,An added advantage to be gained by the use of a device constructed andarranged in accordance with my invention is that a plurality of controlpoints may be provided at the main station in various convenientpositions so that the tune of the transmitter or receiver at thesubstation may be accurately controlled without loss of time by theoperator of the main statlon.

Various other objects and advantages will become apparent from thespecification and therefrom when read in connection with theaccompanying drawing in which the single figure shows the at presentpreferred form of my novel control apparatus.

Referring in particular to the drawing the tuning apparatus at theremote station which, in the drawing, is indicated at B on the right ofthe dotted line, comprises a direct current motor 1 the armature windingof which is connected at one end to the midpoint of the primary windingof a repeater coil 2 in the tone line the other end of the armaturewinding being grounded at 3. The field winding 4 of the motor 1 isconnected through a resistance as, for instance, a lamp 5 to a point onthe battery 6 which serves also as a high potential battery for thereceiver or transmitter. The negative side of the battery 6 is groundedat '7. In order that the motor may be operated at the substation byenergy from the plate battery a lead 8 is provided to connect thearmature of the motor 1 in series through a resistance as, for instance,a lamp 9 and a contact point 10 with a portion of the battery 6. Theshaft of the motor 1 is connected as indicated by the line 11 through agear train 11' and Vernier dial, not shown, to the shaft of a tuningcondenser 12 which is in series with a second variable condenser 13which serves to regulate the net capacity of the unit which is connectedby leads 14 to the tuning circuit not shown of the receiver ortransmitter to be controlled.

At the control station at A on the left of the dotted line in thedrawing a direct current generator 15 having its negative pole groundedis connected in series with a resistance as for instance a lamp 16 and acontact point 17 to a lead 18 connected to the midpoint of the secondarywinding of a repeater coil in the tone line. A second direct currentgenerator 19 having its positive pole grounded is connected or 21. Whenthe contact 17 is closed current from the generator 15 flows through thelamp 16 contact 17, the tone lines and through the armature of the motor1 at the substation. The field winding of the substation being energizedby the plate battery causes the motor 1 to rotate in a predetermineddirection thereby rotating the condenser and altering the tune of thetuning circuit of the transmitter or receiver. By opening the key 1'?and depressing the key 21 current is caused to flow in the oppositedirection, causing the motor 1 to rotate the condenser in the oppositedirection.

While, for purposes of illustration, I have shown but a single controlpoint at the main station it is obvious that several such controldevices may be installed at different appropriate points at the mainstation as, for instance, on all control tables and at the toneamplifiers. The resistances l6 and 20 will, where several such controlpoints are provided, prevent damage in case all of the keys aredepressed at thesame time.

In operation the signals are tuned byshort jabs on either a plus orminus button according to the requirements. The operator tunes thesignal himself and can do this without interrupting his reception. Afterthe apparatus at the substation has been adjusted it requires littleattention, and can be controlled almost entirely from the main station.

Although for purposes of illustration I have fully shown and describedthe at present preferred form of my invention and the operation thereofit will be understood that I do not intend to limit myself therebyexcept as pointed out in the claim attached hereto.

I claim:

In apparatus for controlling from a remote point the position of acontinuously rotatable shaft and for rotating the same the desiredangular. amount in either direction, a plurality of potential sourceshaving opposed terminals connected to ground at said remote point, amotor adjacent said shaft and connected thereto through reductiongearings, said motor having an armature winding, means at said remotepoint for connecting the armature winding of said motor in series withsaid sources of potential alternately whereby current may be caused toflow through said armature winding in the desired direction, a source ofpotential connected with the field winding of said motor, and means atsaid shaft for rotating the same including a circuit for connecting saidarmature winding in parallel with said field winding.

ROBERT I. HATCH.

